It is well known that there is a substantial risk for accidents when pedestrians walk in front of or behind a large vehicle such as a parked bus, for instance at a bus stop, and trying to cross the road. The driver of an oncoming car often has little or no chance of discovering in time a person thus hidden from view by the bus, and therefore cannot stop the car in time to avoid a serious and often fatal accident.
In order to prevent such accidents, some buses have a warning sign permanently mounted on the vehicle and showing a flashing light when the bus is being used as a school bus, but since this sign does not alert other road-user to an actual dangerous situation but merely informs that children are riding on the bus, the sign tends to be ignored by drivers and it is impossible to distinguish between the times when a child might be crossing the road unseen and the many times when this is not happening.
A safety system for preventing such accidents is shown in U.S. Pat. No. 5,132,662 (Burch), where a crossing arm is lowered in front of the bus when a sensor detects the presence of children in the vicinity. The children are thus prevented from crossing the street directly in front of the bus, in order to lower the risk for accidents. This system, however, cannot prevent persons already present in the area directly in front of the bus from crossing the road and has no means for preventing accidents resulting from persons crossing the road behind the bus and being hit by oncoming traffic.
Another safety system is shown by 2008/0106908 (Englander), where a lighting strip along the side of a schoolbus is lit up when a person is detected in the vicinity of the bus, in order to reduce the risk of people being injured by the schoolbus itself. This system serves to alert the driver of the presence of a person nearby and also to warn the person him- or herself of the danger present. However, the system is not aimed at warning other drivers or road-users, and since the detection area is large and also on the side of the bus rather than only in front or in the back, the system will react to a number of cases which does not imply a risk for pedestrians to get hit by other vehicles. The pedestrian will therefore not connect the lighting strip with this risk, and for passing or oncoming drivers the system does not give a clear indication of the amount of danger present.
There is therefore a need for a warning system that can reduce the risk for accidents in a reliable way.